1. Field of the Invention
The present invention generally relates to a scanning system and more particularly relates to a mobile scanner that itself does not have any computing resources and is not energized by a separate power, wherein the operation of the mobile scanner is supported from a computing device and further capable of scanning both transparent and opaque materials.
2. Description of the Related Art
There are many applications that need optical scanners to convert paper-based objects, such as texts and graphics, to an electronic format that can be subsequently analyzed, distributed and archived. One of the most popular optical scanners is flatbed scanners that convert scanning objects, including pictures and papers, to images that can be used, for example, for building World Wide Web pages and optical character recognition. Another popular optical scanner is what is called sheet-fed scanners that are small and unobtrusive enough to sit between a keyboard and a computer monitor or integrated into a keyboard to provide a handy scanning means. Most optical scanners are referred to as image scanners as the output thereof is generally in digital image format.
With the increasing popularity of notebook computers, there is an emerging need for scanners that are even smaller to be carried around like an accessory to the notebook computers. For example, a journalist goes far away from a news bureau to collect information about an important event there. It is considerably useful if a portable or mobile scanner can be used to scan documents on site into a computer that then forwards the electronic versions to the news bureau for immediate news reporting or archival. In the applications like the news reporting, handheld scanners have been used in the past. To be compact, many of the handheld scanners are manually operated, namely a user has to hold a handheld scanner over a scanning document to move from one end to another end so as to scan in the entire scanning document. However, the quality of images is not always satisfactory, typically suffering from jittered motions of the manual operations.
With the emergence of sheet-fed scanners, such as those Paper Port series from Visioneer Inc., handheld scanners are gradually replaced by the sheet-fed scanners. Because a sheet-fed scanner operates automatically, namely a scanning document is well controlled to pass through an image sensor in the sheet-fed scanner, the resultant images are generally satisfactory.
The current sheet-fed scanners in the market are standalone devices whereas they generally operate with a computer. In addition to an image sensor, an illumination source and a motion mechanism, a typical sheet-fed scanner has a microcontroller, memory, post-processing circuitry and interface circuitry. Further to energize all the parts in the scanner to work, there is an external power adapter converting a high AC voltage to a low DC voltage. With all the parts together, a sheet-fed scanner is indeed a self-contained system having an interface to a computing system.
Generally there is a microcontroller in the sheet-fed scanners that controls and operates all the parts to work in synchronization. To reduce the cost of a scanner, the microcontroller in use is typically an 8-bit microprocessor, for example, 8088 from Intel, which is considered nowadays a primitive processor in light of available 32-bit or even 64-bit microprocessors. The overall system performance is thus severely limited by the performance of an 8-bit microprocessor. It is a dilemma of having either a low-cost/low performance scanner or a high-cost/high-performance scanner. There is therefore a great need for a scanner that is low-cost/high-performance. Further there is another need for a scanner that is compact and light weight enough to be truly portable.
In many cases, there is a need to convert transparent objects, such as negative or positive films, transparencies for an overhead projector or X-ray films, into images so that the information in the transparent objects can be, for example, electronically analyzed, distributed or archived. The conversion is currently done through a specially designed film scanner, often bulky and run by a separate service. There is further still another need for mobile scanners that are capable of scanning not only the regular papers but also the transparent materials. The demand for mobile scanners with the dual-scanning capability is ever increasing in both consumer and business markets.